High-frequency oscillator



A ril 27 1926. 1,582,590

R. D. FAY

HIGH FREQUENCY QSCILLATOR Filed Marga 22, 1921 2 Sheets-Sheet 1 m" I 2% A i R i l l I u 1. .3 R R I i 1 i *3 2 *1 I I A ril 27 1926.

' R. D. FAY

- HIGH FREQUENCY OSCILLATOR I 2 Sheets-Sheet 2 Filed March 22, 1921 Patented Apr. 27, 1926.

UNITED STATES PATENT :FFHCE.

RICHARD D. FAY, OF NAEANT, MASSACHUSETTS, ASSIGNOR TO SUBMARINE SIGNAL COMPANY, OF PORTLAND, MAINE, A CORPORATION OF MAINE.

HIGH-FREQUENCY OSCILIIA'I'OR.

Application filed March 22, 1921. Serial No. 454,393.

' To all-whom it may concern:

Be it known that I, RICHARD D. FAY, of Nahant, in the county of Essex and State of Massachusetts, a citizen of the United States, have invented a new and useful Improvement in High-Frequency Oscillators, of which the following is a specification.

My invention relates to a new and useful improvementin sound producing devices and particularly to mechanisms designed to create underwater sounds, although it has other uses. While the present device is capable of producing sounds of any frequency, its design is such as will enable sounds of high frequency to be created without some of the losses of energy inherent in most of the forms heretofore used. In all devices of this kind heretofore made, so far as I know, the movements of the actuating mechanism are imparted only to the central por tion of a diaphragm or plate, one surface of which is in contactwith the medium in which sound waves are to be produced. The result has been that, not only is there larger movement of the diaphragm at its center,- the amplitude decreasing with increasing distances from its. center,-but portions of the. diaphragm tend to vibrate out of unison with other portions or with that of the diaphragm as a whole. The result of this subdivision of the diaphragm into portions vibrating out of phase is equivalent to a large reduction in the effective area. of phragm which creates submarine sound waves. This tendency of the diaphragm to subdivide into parts having widely different conditions of phase becomes increasingly pronounced as the frequency of the vibration im )arted to the diaphragm is increased. This di culty has been entirely overcome in my invention, wherein the portion of my oscillator in contact with the medium in greater portion of the area in contact with the water or other medium are equal, and that the movements of each and every portion of the moving surface in contact with the water is exactly in phase.

- A second important feature of my invention is the method utilized in obtaining the elastic elements. In some of the sound pro- --the diaducers heretofore made the needed elasticity has been obtained by a coupling between elastic discs and an elastic diaphragm. \Vhensuch a design is employed in attempts to make an oscillator operating at frequen- "1QS of 1000 vibrations or more a second, it is necessary to raise the pitch of the coupled discs and diaphragm by increasing their thickness. Not only is there great difiicultv in tuning the elements form-ing this couple so as to obtain the desired frequency, but there is serious danger of the elastic members being strained beyond their elastic limit. I have overcome this difliculty by depending not upon the transverse elasticity of two or more members, but by the utilization of the longitudinal elasticity of a single member, the thickness and length of which can be readily controlled so as to obtain the required frequency of the diaphragm movements without any danger of undue strain upon the elastic member. The weight of the metal piece in contact with the water to which the elastic member is attached is so great that the elasticity of its coupling to the casing can be practically neglected as affecting the frequency of the movements of the elastic member. I am aware that sound producers have been previously designed using longitudinal elasticity rather than transverse, but I am satisfied that I have made a distinct improvement by making my elastic member in the form of a tube rather necessary motion from a single member forming a concentric portion of the entire mechanism. For it is obvious that a single rod attached to the center of the heavy diaphragm member cannot impart motion to this member, as a whole, without introducing large stresses within the member, whereas with a tube acting near the periphery of the member, the force exerted is so distributed as to produce a motion of the member as a Whole with comparatively small internal stresses.

Another important feature of my invcn-- tion is that the adjustment of the internal Working parts of my sound producer is not affected by the differences in pressure exerted upon the sound producing member when the apparatus is immersed at difierent depths. In no other mechanism, so far as I know, in which the longitudinal vibrations of a rod or its equivalent are used is this lltl most important feature, obtained. In my device under ordinary conditions of use the end of the vibrating member having the maximum motion has no restriction to its movement as far as the mechanical arrangements and dimensions are concerned, and, the mechanism will work, as far as this feature is concerned, equally freely in any depth' of water and even in air.

Another important feature in design is the fact that all conductors carrying the this construction the air gap and hence the reluctance of the magnetic circuit is reduced and the electrical efficiency of the mechanism greatly augmented.

My invention will 'be understood by reference to the drawings, in which- Figure 1 is a longitudinal section of a device embod ing my. invention;

Figs. 2 an 3 being sections, respectively, on lines 22-'*and 3-3 of Fig. 1.

In this figure A is a mass of iron or steel which is moved backward and forward to produce sound waves. Its front surface a is in contact with the medium in which the sound waves are to be produced and corresponds with the.diaphragm heretofore used in devices of this kind. In order to permit the requisite movement of this steel piece A, the thickness of metal is reduced at a, this reduction being sufficient to allow the required amplitude of motion of the central rigid portion of the steel piece A. I A slot is out within the steel piece at A in which is wound the requisite number of turns of insulated copper wire B connected with a direct current generator (not shown) to make of the steel piece a powerful electromagnet. Onthe surface of this steel piece A are Wound two connected coils of insulated wire E and F, designed to carry the alternating current used to produce the required move:

- other-end of the elastic member G is secured a second tube of elastic material G which tube is arranged coaxiallywith the first tube and with "the steel piece A. The tubes G and G are held together at their inner ends by a spacer H and two stiffening rings J and K. The tubes, spacer and stiffening rings are held together without the possibility of lost motion in any suitable manner. As shown these are riveted together by rivets h. A copper tube L is secured within the 'free end of thetube of larger diameter G to form an integral portion-of that tube. A collar of magnetic material, such as iron M, is held firmly in place around the steel piece A and coaxial with it. A tube or pipe N with flanges is bolted to the periphery of mass A and serves to form a portion of a case to contain the entire device. The joints between the tube N and the mass A'and the head N should be packed to keep out the water. The collar M may be attached to the interior of the tube N. -The open end of the tube N is closed in by a head N which is bolted thereto and has an opening n which may carry a gland (not shown) for the conductors leading from the oscillator to sources of current. There are many kinds of glands suitable for this purpose and they are so well known that further description thereof seems unnecessary. The case N together with the head N when the former is bolted to mass A, forms a complete and watertight casing for the mechanism. Z is a ring of insulating material. A test valve N is preferably mounted on thehead N to be used in testing the joints to determine whether or not they are watertight. For this purpose the screw 02. .may be removed and a vacuum pump connection be applied to the nipple. If the joints prove tight the connection is removed and'thc screw 11. is screwed home to hold the ball valve in place.

)Vhen direct current is passed through the windings B the mass of iron A is magnetized. The lines of force pass from A through the air gap between the magnet A and the copper tube L and through the steel tube to which the copper tube L is attached and through the ring of magnetic material M. The result is that there is a strong magnetic field created in the space in which the copper tube is free to move. The connections of the coils E and F, designed to carry the alternating currents, are such that when alternating current passes through them, powerful currents are induced in the copper tube and combine to force the copper tube longitudinally depending upon their direction. The lines of force are indicated in Fig. 1 of the drawings in'which the direction of the lines of force are indicatedby arrows marked 'd-0 and a-c which in Fig. 3 inclicate the direct and alternating current leads. The reactive forces on coils E and F also assist inmoving the mass A.

In operation, a direct current is passed th rough the field winding Bv and an alter nating current of a frequency equal to the natural frequency of the vibrating system, is passed through the alternating current coils E and F. The alternating current produces an elongation or compression of the elastic members G and G which motion is imparted to mass A tending to force mass A inward and outward, but with an amplitude of motion relatively much smaller than that of the copper tube. It will be noted that there is no practicallimit to the movement of the free end of the copper tube L so that the amplitude of motion can be as great as the material of the tubes G and G and their connections will withstand.

P is a block of insulating material mounted on the piece A and carrying the necessary binding posts 79, p for the wires which pass up thereto through the passages 2 the alternating circuit wires being lettered p and the direct circuit wires being lettered 12 I do not mean to limit myself to the-precise construction shown for it will be evident to one skilled in the art that it may be otherwise embodied.

What I claim as my invention is l. A sound producing device comprlsing an active member one surface of which is adapted to contact with the medium through which sound is to be sent and having an elastic flange, a stationary support, said flange being attached to said support, and means for moving said active member comprising a metallic cylinder of high electric conductivity having a tube of elastic me,- tallic material rigidly connected thereto and to said active member whereby a large amplitude of motion given said metallic cylinder will cause a smaller amplitude of motion of said active member, and electric means for vibrating said metallic cylinder.

2. A sound-producing device comprising a casing, a vibratory member located therein and yieldingly attached thereto, said vibratory member being in. itself substantially rigid whereby the vibrations of the part of its body out of unison with the rest of its body will be prevented, a second vibratory member and electrical means for vibrating it, and connections between said vibratory members whereby the movements given to said second vibratory member will be transmitted to said first-named member with loss of amplitude, 'said connections comprising two concentric elastic metallic tubes, the

adjacent outer ends of which are attached together, their inner ends b'eingattached respectively one to each of said vibratory members.

3. A sound-producing device comprising a casing, a vibratory member located therein and yieldingly attached thereto, said vibrato member being in itself substantially rigid whereby the vibrations of the part of its body out of unison with the rest of its body will be prevented, a second vibratory member and electrical means for vibrating it, and connections between said vibratory members whereby the movements given to said second vibratory member will be transmitted to said first-named member with loss of amplitude, said connections comprising two concentric elastic metallic tubes, the adjacent outer ends of which are attached together, their inner ends being attached respectively one to each of said vibratory members, said tubes being of substantially the diameter of the vibratory portions of the members to which they are attached.

4. A sound-producing device comprising a casing, an active member attached thereto, said vibratory member being in itself substantially rigid whereby the vibrations of the part of its body out of unison with the rest of its body will be preventedand lo- .cated to close one end thereof, a cylinder having high electrical conductivity, electric means for causing the vibration of said cylinder, and connections between said cylinder and said member comprising a tube of elastic material whereby the mechanical vibrations of said cylinder will set up mechanical vibrations of less amplitude in said member. 5. A sound producing device comprising a casing, a diaphragm member closing the opening of said casing, said diaphragm having a thin annulus forming a yielding member and a cylindrical center mass of magnetic material, a winding about the cylindrical portion whereby a radial magnetic. field may be set up, an alternating current coil and a vibratory cylinder of high electric conductivity situated in said magnetic field, and amplitude transformation means connecting said vibratory cylinder with the cylindrical center mass whereby said latter mass vibrates uniformly over its whole outer surface.

6. In a sound producing device comprising a casing, a diaphragm member closing the opening of said casing, said diaphragm having a thin annulus forming a yielding member, and a heavy center mass of magnetic material forming a radial magnetic field, electrical means for varying the strength of said magnetic field, means vibrated by the electrical action of said elec trical means and means to impart said vibrations to the heavy center mass of said diaphragm whereby a substantial uniform motion will be obtained over the entire vibrating surface.

RICHARD D. FAY. 

